Primary exercises
- Manually created factor.
In a study participants were asked whether their sport activity is
none, oncePerWeek, severalPerWeek
or daily.
Build a proper factor for the responses below and store it in a variable
w.
Print the factor.
Write the code to count the numbers of occurrences of each level and
print the counts.
severalPerWeek, none, none, oncePerWeek, oncePerWeek, oncePerWeek, oncePerWeek, ?, none, none
v <- c( "severalPerWeek", "none", "none", "oncePerWeek", "oncePerWeek", "oncePerWeek", "oncePerWeek", NA, "none", "none" )
w <- factor( v, levels = c( "none", "oncePerWeek", "severalPerWeek", "daily" ) )
w
[1] severalPerWeek none none oncePerWeek oncePerWeek oncePerWeek oncePerWeek <NA> none none
Levels: none oncePerWeek severalPerWeek daily
fct_count( w )
# A tibble: 5 × 2
f n
<fct> <int>
1 none 4
2 oncePerWeek 4
3 severalPerWeek 1
4 daily 0
5 <NA> 1
- A factor with a random content.
Read help about the function sample.
Then study and try the following lines of code to understand the
results.
Next, understand why an error is generated and use replace
argument to generate a vector with 100 samples.
Store this vector in a variable v and build a factor
w from it.
Finally, count the numbers of occurrences of each level in
w.
Ensure, that levels are in order provided in the variable
lvs.
lvs <- c( "none", "oncePerWeek", "severalPerWeek", "daily" )
sample( lvs, 3 )
[1] "daily" "none" "severalPerWeek"
sample( lvs, 3 )
[1] "severalPerWeek" "oncePerWeek" "none"
sample( lvs, 3 )
[1] "daily" "none" "severalPerWeek"
sample( lvs, 100 )
Error in sample.int(length(x), size, replace, prob): cannot take a sample larger than the population when 'replace = FALSE'
v <- sample( lvs, 100, replace = TRUE )
w <- factor( v, levels = lvs )
w
[1] severalPerWeek severalPerWeek severalPerWeek none oncePerWeek none daily oncePerWeek oncePerWeek oncePerWeek
[11] severalPerWeek severalPerWeek daily oncePerWeek none oncePerWeek daily oncePerWeek severalPerWeek severalPerWeek
[21] oncePerWeek none none daily severalPerWeek oncePerWeek severalPerWeek none oncePerWeek severalPerWeek
[31] none severalPerWeek severalPerWeek daily none daily daily daily none daily
[41] severalPerWeek none severalPerWeek none daily daily none severalPerWeek oncePerWeek none
[51] daily severalPerWeek daily severalPerWeek none daily severalPerWeek severalPerWeek none daily
[61] none severalPerWeek oncePerWeek none severalPerWeek daily severalPerWeek daily daily none
[71] none severalPerWeek none severalPerWeek oncePerWeek daily daily severalPerWeek oncePerWeek oncePerWeek
[81] severalPerWeek oncePerWeek severalPerWeek daily oncePerWeek oncePerWeek none daily none daily
[91] severalPerWeek oncePerWeek severalPerWeek daily oncePerWeek severalPerWeek severalPerWeek severalPerWeek oncePerWeek daily
Levels: none oncePerWeek severalPerWeek daily
fct_count( w )
# A tibble: 4 × 2
f n
<fct> <int>
1 none 22
2 oncePerWeek 21
3 severalPerWeek 32
4 daily 25
- Reordering factor levels.
When a factor is shown on an axis of a plot, the order is given by its
levels.
The factor w from the previous exercise will be then shown
in this order: none, oncePerWeek,
severalPerWeek, daily.
But for a picture in a manuscript the following order might be needed:
daily, severalPerWeek,
oncePerWeek, none.
Apply to w one of the fct_ functions from the
tidyverse library to produce a factor w2 with
the requested order.
Show the levels of w2.
Again show the number of elements of each level in w2 and
compare it with the table of the previous exercise.
w2 <- fct_relevel( w, c( "daily", "severalPerWeek", "oncePerWeek", "none" ) )
levels( w2 )
[1] "daily" "severalPerWeek" "oncePerWeek" "none"
fct_count( w2 )
# A tibble: 4 × 2
f n
<fct> <int>
1 daily 25
2 severalPerWeek 32
3 oncePerWeek 21
4 none 22